This is really cool. Jeri Ellsworth made some videos several years ago about homemade silicon transistors, but it was impractical due to the low precision and

This is really cool. Jeri Ellsworth made some videos several years ago about homemade silicon transistors, but it was impractical due to the low precision and large size. Getting down to 5 um is a few orders of magnitude worse than a top end chip foundry today, but it's at least useful and you can fit all of the necessary equipment into a spare bedroom.